1. Field of the Invention
The present invention relates to a liquid jet recording head used for a liquid jet recording apparatus that records on a recording sheet by discharging ink from the discharge ports of the orifice plate thereof.
2. Related Background Art
The liquid jet recording apparatus performs its recording on a recording sheet by discharging ink (recording liquid) as liquid droplets from the discharge ports arranged for the orifice plate of the liquid jet recording head. In accordance with the driving signals transmitted from the main body of the liquid jet recording apparatus, ink in each of the liquid flow paths is heated by each of the discharge energy generating elements which is arranged in each of the liquid flow paths so as to create the changes of state of ink for the formation of bubbles. Then, on the basis of the voluminal changes at the time of the bubble formation, ink is discharged from each of the discharge ports.
More specifically, as the discharge energy generating elements, the electrothermal transducing devices are used to generate heat when energized in accordance with the recording signals. The discharge energy generating elements are formed on a silicon substrate by the application of the thin film formation technologies and techniques in semiconductor field.
In general, the liquid jet recording head comprises a substrate having a plurality of discharge energy generating elements on it, and a ceiling plate that covers the upper part of the substrate. The ceiling plate comprises an orifice plate having the liquid flow paths (nozzles) that face the discharge energy generating elements, respectively, and the ink discharge ports; an ink liquid chamber for supplying ink to each of the liquid flow paths; and ink supply port through which ink is supplied to the ink liquid chamber.
The orifice plate is a sheet-type member of several tens to several hundreds of xcexcm. For this sheet type member, a number of fine holes are formed as ink discharge ports. Then, as the method to form these fine holes efficiently in high precision, there are utilized a laser processing, an electroforming, a precision press work, a precision molding, or the like.
On the other hand, each liquid flow path (nozzle) is formed by means of a groove having a width of several tens of xcexcm and a depth of several tens of xcexcm. Many numbers of such grooves are formed at pitches of several tens of xcexcm. In order to arrange these fine grooves to face the discharge energy generating elements in high precision, respectively, there is used for the manufacture thereof, precision molding, such as an injection molding, a transfer molding, an compression molding, an extrusion molding, an injection mold, ceramics injection; the fine laser processing, such as the excimer laser, the YAG laser; or the semiconductor thin film formation technologies and techniques, such as the silicon anisotropic etching, the photolithography, among others.
The ceiling plate is formed by means of the precision processing as described above. Particularly, the method that adopts the precision molding is extremely effective in that the member can be manufactured at lower costs, and in that the complicated configuration can be molded easily. So far, the ceiling plates are formed in various modes.
As the molding resin material, the resin material used, such as polysulfone, polyether sulfone, polyphenylene sulfide, denatured polyphenylene oxide, polypropylene, polyimide, or liquid crystal polymer (LCP) has an excellent resistance to ink.
For the molding of the ceiling plate, the most difficult techniques are to fill in the thinner thickness portion of the orifice plate, and transfer the fine portions of the liquid flow path walls stable as well. Therefore, the highly precise molding of the ceiling plate is performed by adopting various simulation techniques, such as the flow analysis or the precise mold machining techniques, at the same time, using a precise high-speed injection molding machine or a material having the high flowability for that purpose.
The injection molding is the most popular precision formation method. However, it is possible to implement the molding of a precise ceiling plate by the adoption of this method with the thorough control of the injection molding condition, such as the injection speed, the injection pressure, the dwell, the temperature adjustment of the metallic molds, the temperature adjustment of the resin, as well as with the structural devices of the metallic molds, such as degassing, the adjustment of dowel positions, or gate configuration, and further, by the positive utilization of the modern injection molding techniques, such as the pressure control in the interior of the metallic molds, the localized heating of the metallic molds, the vibration molding by use of the ultrasonic waves, or the injection molding using the compression in the interior of the metallic molds.
In this respect, the orifice plate may be molded integrally with the ceiling plate or molded separately from the ceiling plate. The structure of the ceiling plate in these cases may be selected arbitrarily depending on the component structure of the entire body, the structure of assembling apparatus, the method of laser processing, or the like. In either case, however, it is required to adopt a highly precise molding technique.
For example, the most difficult part of the ceiling molding is the filling of the molding resin into the fine portions such as the flow path walls. It is generally impossible to perform the sufficient filling in this portion just by the adoption of the injection processing step. In other words, for the injection processing step, the resin viscosity is made lower by the utilization of the temperature adjustment or sealing heat generation, and the flowability of the resin is enhanced. Then, before the resin is cooled down, it is filled in the metallic molds as quickly as possible. At this juncture, however, the condition of resin filling is still incomplete in the location where the resin flow is stagnated or at the corners, in the minute portions, or the like. Then, if the process proceeds to the step of dwelling, the pressure thus dwelled tends to act upon all the places in the interior of the metallic molds, and the transfer is performed to the portion where the filling has been insufficient in the injection step. As a result, if the filling is insufficient in the injection step, the pressure thus held tends to be concentrated on the locations where the filling is not sufficient, hence making it impossible to allow the pressure thus held to act upon the entire area of the interior of the metallic molds.
FIG. 1 is a view which schematically shows the conventional liquid jet recording head as described above. In FIG. 1, this liquid jet recording head comprises the substrate (hereinafter referred to as a heater board) 100 having the ink discharge pressure generating elements arranged on it, and the ceiling plate 500 having the irregular portion which constitutes the ink liquid chamber 600 that contains recording liquid (hereinafter referred to as ink) and the liquid flow paths (nozzles) 700 when the ceiling plate is bonded to the heater board 100. Then, above the ink liquid chamber 600, the ink supply port 1000 is arranged to be communicated with the ink liquid chamber 600.
Also, in front of the liquid flow paths (nozzles) 700, the orifice plate 400 having the ink discharge ports on it for discharging ink is integrally formed with the ceiling plate 500 or bonded to or coupled with the ceiling plate 500 so that the ink discharge ports are communicated with the liquid flow paths 700.
The heater board 100 is adhesively fixed to the supporting substrate (hereinafter referred to as a base plate) 300 by the application of the bonding agent 306 or the like. The ceiling plate 500 is positioned and bonded so that the liquid flow paths (nozzles) 700 of the ceiling plate 500 are in agreement with the heater units 100a of the ink discharge pressure generating elements arranged on the heater board 100, respectively. The orifice plate 400 is arranged like an apron on the front edge of the base plate 300. Also, the ink chamber 600 of the ceiling plate 500 receives the ink supply from an ink tank (not shown) through the ink supply port 1000.
For a liquid jet recording head of the kind, when the liquid flow paths (nozzles) 700 and the heater board 100 are bonded to form the ink flow paths, the bonding agent may enter the interior of the liquid flow paths (nozzles) 700 if the sealing agent, the adhesive agent, or some other bonding agent is used for bonding the liquid flow paths (nozzles) 700 and the heater board 100 together. Thus, the configuration of the liquid flow paths (nozzles) 700 is subjected to the deformation or there is a fear that the liquid flow paths (nozzles) 700 are partly clogged. Therefore, the bonding is made by mechanically compressing at least the liquid flow path portion in order to preclude the possibility of such imperfection.
Now, hereunder, this structure will be described. The heater board 100 and the ceiling plate 500 are positioned in the direction (indicated by arrows E in FIG. 1) which is in parallel to the ink discharge direction by allowing the front end surface of the heater board 100 to abut upon the orifice plate 400. Then, the heater board 100 and the ceiling plate 500 are bonded. Subsequently, the nails 507 each arranged on the lower part of each end of the pressure spring 900 are inserted into the holes 307 provided for the base plate 300. Thus, the folded portions 507a of the nails 507 are hooked to the lower end of the base plate 300. In this way, the pressure spring 900 is allowed to exert its mechanical pressure to the contacted portion from above the liquid flow path walls of the ceiling plate 500.
Therefore, the liquid flow path walls of the ceiling plate 500 and the heater board 100 are closely in contact by the application of the mechanical compression as described above.
However, in such case of the mechanical compression, the compressive force thus exerted does not act upon the outer walls of the ink liquid chamber 600 and other bonded portions sufficiently, although it is good enough to allow the heater board 100 to be in close contact, because the liquid flow path walls receive the direct weighting from above. Therefore, it is extremely difficult to allow all of these components to be in close contact with the heater board 100 exactly.
On the other hand, there is a method for retaining the outer wall portion of the ink liquid chamber to be in close contact by arranging pressure means separately to compress the outer wall portion of the ink liquid chamber. However, with this method, the repulsive force of the compression exerted on the ink liquid chamber tends to act upon the liquid flow path walls, and there is a fear that the close contactness of the liquid flow path walls is impeded. Hence, this method cannot be regarded as an effective one.
Under the circumstances, there are created fine steps in general on the lower faces of the liquid flow path walls and the outer wall portion of the ink liquid chamber, and when the lower face of the liquid flow path walls is in close contact with the heater board 100, a gap is formed between the lower face of the outer wall portion of the ink liquid chamber and the heater board 100. Then, sealant is applied to this gap to secure the airtightness between the outer walls of the ink liquid chamber and the heater board 100.
Here, as a matter of course, if this gap becomes larger, it may cause the defective sealing. If, on the other hand, if the gap is made smaller, the lower face of the ink liquid chamber and the heater board 100 are in contact to impede the close contactness between the liquid flow path walls and the heater board 100.
Therefore, in order to apply the sealant exactly to the gap formed between the lower face of the outer wall of the ink liquid chamber and the heater board 100, the molding process should be controlled so that the steps between the lower faces of the liquid flow path walls and the outer walls of the ink liquid chamber are formed in the desired value.
The sealant is used for the bonded portion between the units of the liquid jet head that should be in contact with ink for the prevention of external ink leakage. More specifically, such bonded portions are the one between the back face of the orifice plate 400 and the front end face of the heater board 100, the back face of the orifice plate 400 and the front end face of the base plate 300, and the bonded portion between the ceiling plate 500 and the heater board 100, among some others. The sealant between each of them is caused to flow over within a specific area by means of the capillary force generated between each of the gaps and the sealant. The configuration of each component is devised so as not to allow the sealant to flow over into any other regions than those specifically designed, and the sealing is effectuated with the careful control of the part dimensions, the viscosity of sealant, and some others.
FIG. 2 is a cross-sectional view which shows the bonded state of the ceiling plate 500 and the heater board 100. As shown in FIG. 2, the pitches of the liquid flow paths (nozzles) 700 of the ceiling plate 500 and the pitches of the heater units 100a on the heater board 100 are set equally, and the machining of both components and the positioning thereof are made in high precision to enable each of the liquid flow paths (nozzles) 700 and each heater unit 100a to face each other in high precision for the enhancement of ink discharge accuracy.
Also, if a part of ink drops and flows to adhere to the circumference of the discharge ports when ink is discharged from the liquid jet recording head, it may cause the deviation of ink discharge direction or if the adhesion of ink is left intact for a long time, it is solidified to cause the ink clogging. In general, therefore, it is practiced to give the water repellent treatment to the entire surface of the orifice plate or to the circumference of the discharge ports locally. In this way, it is attempted to prevent ink from remaining on the circumference of the ink discharge ports. A water repellent treatment of the kind is given by injection or coating on the surface of the ceiling plate after the molding thereof or by the eutectoid plating, among some others.
As described above, the ceiling plate is molded integrally with the liquid flow path walls, the orifice plate, the ink liquid chamber, the ink supply port, and others to present a complicated configuration having minute portions and thinner thickness portions as well. Thus, in order to mold the ceiling plate, it is required to exercise the molding accuracy, such as dimensional accuracy, dimensional stability, transfer precision, fine deformation, as well as the filling capability with respect to the thinner thickness portions. To meet such requirement, the thorough control is needed for the molding environment, molding condition, material quality, and some others, which makes it very difficult to obtain the stably finished products.
Also, the ink liquid chamber is molded with the largely recessed portion on the contact surface thereof, which is open to the heater board, while the ink supply port is the through hole which is communicated with the ink liquid chamber. By the presence of these ink paths which serve as the ink supply means, there are provided a largely recessed portion and the through hole for the ceiling plate. As a result, when the ceiling plate is molded, several welds are naturally created in some locations.
Here, resin generates gas from inside when heated at a high molding temperature. In general, some method is adopted to enable the gas thus generated to escape to the outside of the metallic mold with the gas vents arranged at joints of the mold dowels or at the corners thereof. However, in the vicinity of each weld, a gas of the kind is not released to the outside of the metallic mold, but it may be stagnated there in some cases. In other words, the gas pushed by the fused resin that flows from behind joins the gas residing in the portion where the weld has been formed, and being sandwiched by the skin layers of resin approaching bidirectionally, the gas thus joined may lose the place to escape, and stagnated in that area eventually. As a result, the gas is confined inside completely. In this manner, the probability is high that the gas generated from inside the resin is confined in the weld portions without being released outside the metallic mold entirely, and that it remains residing in such portion.
Likewise, the same description may be made of the air residing in the interior of the metallic mold beforehand. In other words, the air deposited in the interior of the metallic mold before resin is filled is expelled from the gas vents by the pressure of resin which is injected at the time of filling. However, a part of the air should remain inside the metallic mold by being enclosed by the resin thus injected. In the weld portions, in particular, the probability is high that the air is enclosed more inside the resin that approaches bidirectionally as in the case of the gas as described earlier.
Thus, the gas and the air that are stagnated in the welds or the like are highly pressurized when receiving the filling pressure of resin, and this condition may impede the resin filling eventually. As a result, the transferability of the finished product is affected to make its precision inferior. For the conventional ceiling plate molding, the consideration should be given to these aspects carefully, and the molding condition should be controlled as to the gate arrangements, the gate sizes, the sprue sizes, and the runner sizes, the injection speeds, the injection pressures, the dwell, the molding temperatures, the inner pressures of the metallic mold, and each cycle time among various others.
However, for the liquid jet recording apparatus used as the output equipment for a personal computer, a copying machine, a facsimile equipment, or the like, it is now a prerequisite that the apparatus provides a resolution that matches the silver salt film. Along with this requirement, the size of the discharge ports, the width of liquid flow paths, the size of the heaters, and the arrangement pitches therefor should become more minute.
For example, when the ceiling plate that has a highly densified nozzles capable of performing the 1,200 dpi discharge at a time should be formed, there is a possibility that it becomes difficult not only to carry out the control of the forming conditions as described above, but also, it becomes impossible to remove the gas and the air residing in the vicinity of the welds. This incapability of gas or air removal may become a critical problem in the ceiling plate molding.
The portion of the finished ceiling plate that requires the highest precision is the flatness of the lower face of the liquid flow path walls. Usually, however, there occurs a warping of approximately several xcexcm on the lower face of the liquid flow path walls of the ceiling plate. Therefore, this warping of the lower face of the liquid flow path walls are corrected by means of the pressure spring that compresses the liquid flow path walls downward from above it. At the same time, the lower face of the liquid flow path walls are kept in close contact with the heater board. Consequently, the ceiling plate which is in close contact with the heater board is not allowed to exert the inner stress or the inner distortion.
Then, if such inner distortion of the ceiling plate becomes greater, the adverse effect is produced on the ink discharges. In other words, if the warping of the lower face of the liquid flow path walls is corrected to keep them in close contact, the orifice plate is also warped accordingly by being influenced by the distortion of the circumference of the liquid flow path walls.
If the orifice plate warps, there is a possibility that the relative orientations and the relative positions of the discharge ports which are arranged in plural numbers are caused to change, hence degrading the accuracy in which ink droplets are impacted to lower the print quality eventually.
To counteract this phenomenon, there is a method in which the ceiling plate is molded by a material whose elasticity is greater so that the robustness of the ceiling plate is enhanced to make the inner distortion smaller when it is kept in close contact. If the robustness of the ceiling plate is made greater, it becomes difficult to correct the warping of the lower face of the liquid flow path walls. Then, there is a fear that defective contactness takes place with respect to the heater board. On the other hand, there is a method in which the compression of the pressure spring is made greater so that the entire region of the liquid flow path walls may be corrected. However, if the compressive force becomes greater, the inner stress of the ceiling plate is increased to make the inner distortion greater still.
If the contactness between the liquid flow path walls and the heater board is insufficient, the adjacent liquid flow path walls themselves are allowed to provide a gap with the heater board among a plurality of the liquid flow paths molded by bonding the liquid flow path walls and the heater board. As a result, the discharge pressure exerted on the heater board tends to be dispersed to the adjacent liquid flow paths to make the ink discharge speed unstable when recording is performed, and the ink droplets are twisted or ink is not discharged from the intended discharge ports when the recording signals are applied, but discharged from the adjacent discharge ports instead. Consequently, printing disturbance may take place to invite the degradation of the quality of recorded images.
Therefore, in order to effectuate the close contact between the lower face of the liquid flow path walls and the heater board exactly, there is a need for the molding of the ceiling plate with the liquid flow path walls whose warping is kept as small as possible.
In accordance with the conventional example, the ceiling plate is molded with a material whose elastic modulus is comparatively small so that the consideration is given to making the warping correction smoother for the liquid flow path walls. Here, in the conventional case, it is arranged to keep the amount of warping of the lower face of the liquid flow path walls at approximately 5 xcexcm against the length of 13 mm of the liquid flow paths (closely contact surface) in the arrangement direction.
However, there is almost no influence to be exerted on the print quality even if the warping of approximately 5 xcexcm is corrected for the close contact, but if it is intended to make the robustness of the ceiling plate greater, the warping of 5 xcexcm on the lower face of the liquid flow path walls becomes a greater value, thus making it difficult to keep the liquid flow path walls in close contact.
Also, for the intended development of the ceiling plate which is provided with nozzles in a higher density, the 5 xcexcm warping of the lower face of the liquid flow path walls, which has not presented a problem in accordance with the conventional art, becomes a problem which should be solved. In other words, the amount of the inner distortion of the ceiling plate that takes place after the close contact, which has not presented any problem conventionally, may exert a greater influence on the ink flow path unit if the liquid flow paths should be arranged in a higher density. Then, the ink discharge characteristics are degraded after all.
Therefore, it is necessary to overcome the problems existing in the conventional art along with the development of the liquid jet recording apparatus which is capable of recording in a high image quality. More specifically, it is preferable to form the ceiling plate having a greater rigidity in a better forming precision with the better surface precision of the lower face of the liquid flow path walls, with a smaller inner distortion after close contact. Then, to implement the ceiling plate in this mode, the level of the production technologies and techniques should be enhanced still more.
On the other hand, for the resin molding, it becomes more important to select the material which is excellent in presenting the dimensional stability in higher precision, without which it is not easy to enhance the level of the precision molding techniques, of thinner thickness portions. There is naturally a limit to the molding by the adoption of pure materials which do not contain any fillers. Then, to achieve these objectives, it is necessary to improve the properties of the material by filling the ceramics or metallic fillers.
Now, however, there are the following problems encountered in forming the ceiling plate by use of resin filled with the fillers or the like.
Now, firstly, there is a problem with respect to the laser processing. When the orifice plate is molded with resin, the fine holes provided therefor are made by the ablation process using the excimer laser. Now, with the excimer laser processing, the filler portion cannot be ablated. As a result, on the inner surface of each fine hole, fillers remain as extrusions or there is a fear that the fillers fall off from the surface to form recessed portions. The inner surface of each fine hole cannot be made smooth to cause the defective ink discharges.
Secondly, there is a problem concerning the production of metallic molds. Since the liquid flow path walls of the ceiling plate is each in a fine configuration, the mold dowel needed for transferring this configuration should be machined in an extremely high precision. Also, this mold dowel cannot be easily machined by use of a general machine tool, making it necessary to use a specially built machine tool with a special material. It also takes a long time to carry out such highly precise machining. Then, a mold dowel of the kind used for the transfer of the liquid flow path walls increases the manufacturing costs of the molds considerably as a whole. Moreover, this mold dowel is caused to slidably rub the fused resin at the time of injection, and to slidably move along the finished product when removed from the mold. Consequently, if the ceiling plate is molded by a material which is filled with fillers or the like, the mold dowel is quickly worn out to reduce the durability of the molds, which leads to the reduction of the ceiling plate productivity after all.
Thirdly, there is a problem concerning the flowability of the material to be used. For the ceiling molding, the selected material should present a good flowability in order to transfer the fine portions thereof exactly. In general, however, if resin filled with fillers, it tends to be subjected to the inferior flowability. This tendency is disadvantageous in transferring the thinner thickness portions and fine portions.
Fourthly, there is a problem concerning the fillers that impede the flow and transfer of resin. Since the width of each of the liquid flow path walls is as fine as several xcexcm to tens and several xcexcm in its , dimension, there is a possibility that the dimension of each of fibers, beads, or some other filler grains becomes larger than the thickness of each liquid flow path wall. If the ceiling plate is molded with resin filled with fillers, there is a possibility that not only the fillers are not transferred to the inside of the liquid flow path walls, but the fillers are stagnated in such a state of being bridged over the entrance portion of each groove so as to block the flow of fused resin that follows to run. As a result, the flow of resin is disturbed. Also, if the molding is made with resin filled with fillers, there is a case where the fillers are educed on the surface of the finished product. The fillers thus educed slidably rub the metallic mold at the time of removing it. As a result, the fillers may fall off from the surface layer of the finished product. Further, the fillers are not filled in the liquid flow path wall portions, the intended improvement of the performance of the liquid flow path wall portions does not act as effectively as anticipated.
To counter act this tendency, it may be possible to fill resin with the ultrafine filler particles of several xcexcm to several nm which is smaller than the thickness of each liquid flow path for the molding of the ceiling plate. However, it is extremely difficult to disperse such ultrafine filler particles uniformly in the base resin. For that matter, it is extremely difficult to supply the stably prepared material.
Also, there is a need for the adoption of a special dispersion technique to disperse the ultrafine filler particles uniformly in the base resin, and at the same time, the surface treatment is needed for use of the ultrafine filler particles with the application of silane coupling agent or the like. Therefore, it costs extremely high to obtain the resin material which is filled with the ultrafine filler particles of the kind.
As described above, if the ceiling plate is molded by the resin whose physical property is enforced by the fillers thus filled in it, the enhancement of the forming precision is possible. However, due to the hindrance to the laser processing, the lowered quality of the finished product, the reduced durability of the metallic mold, and the inevitable use of higher cost molding material, this means is not necessarily an effective one for the purpose.
Therefore, in accordance with the conventional molding method, it is difficult to enhance the forming precision of the ceiling plate, the surface precision of the lower face of the liquid flow path walls, the robustness of the ceiling plate, and the like. To overcome such difficulty is the subject which should be dealt with to develop a highly densified liquid jet recording head.
Now, hereunder, the description will be made of the problems concerning the environments under which a liquid jet recording head is used and reserved.
If the temperature changes are great in the environment under which the liquid jet recording head is used, the voluminal expansion or contraction takes place with respect to various parts that constitute the liquid jet recording head. Then, there is a possibility that the positions of the bonded portions of the head are caused to deviate correlatively. The liquid flow path walls which are molded by the close contact between the ceiling plate and the heater board may produce an adverse effect on the ink discharge performance if the relative positions between them should be deviated greatly, because the configuration of the liquid flow path walls is extremely fine having the pitches of several tens of xcexcm between each of them.
Now that the materials that form the heater board and the ceiling plate are different, a force tends to act upon them to deviate the relative positions between them. In other words, due to the inner stresses generated by the thermal expansion corresponding to the temperature changes, the heater board and the ceiling plate present the voluminal changes individually, which may bring about the deviation of the relative positions of the liquid flow path walls and the heater board, which are arranged to face each other and bonded.
On the other hand, the liquid flow path walls are compressed mechanically as described earlier. Due to this compression, a friction force is allowed to act upon between the liquid flow path walls and the heater board. With this friction force and the mechanical strength of the liquid flow path walls themselves, it is arranged to prevent the deviation of the relative positions between them.
Now, however, the action of this mechanical compression becomes less effective at the leading end portion of the discharge ports. As a result, although extremely minute, the relative positions between them may take place at the leading end portion of the discharge ports in some cases.
Further, for the liquid jet recording head which is provided with the discharge ports capable of obtaining the resolution of 1,200 dpi per discharge, for example, the nozzles are arranged in higher density with the extremely smaller dimension of the thickness of each liquid flow path wall, such as approximately several xcexcm to several tens of xcexcm. As a result, the friction force and the mechanical strength of the liquid flow path walls are made lower. Then, there is a possibility that the deviation of the relative positions between the liquid flow path walls and the heater board takes place, making it difficult to suppress such deviation of the relative positions.
In order to suppress such deviation of the relative positions, there is a method in which the compression of the pressure spring is increased or the friction force is increased on the contact surface of the liquid flow path walls. However, the greater the compression of the pressure spring, the greater becomes the inner distortion of the ceiling plate when the ceiling plate is in close contact. Then, the print quality is allowed to become inferior. Further, under the high temperature environment, the liquid flow path walls receive the thermal stress and weight of the pressure spring. Eventually, therefore, there is a possibility that the liquid flow path walls may present buckling, bending, or some other plastic deformation. For that matter, it is not advisable to increase the compression of the pressure spring too much.
Also, it may be possible to adopt the method whereby to form the ceiling plate with resin having a smaller linear expansion coefficient as another counter measure.
For example, it may be possible to contain fibers, beads, or some other fillers in polysulfone, polyether sulfone, denatured polyphenylene oxide, polyphenylene sulfide, polypropylene, polyimide, polyamide-imide, epoxy, polyethylene, LCP or some other resin which has an excellent property to resist ink (chemical resistance) so as to make its linear expansion coefficient smaller which matches metal. In this way, the LCP or resin material or pure material can be used for the molding of the ceiling plate.
When the ceiling plate is molded with the resin material which is enforced by fillers, there is an effect that the linear expansion coefficient of the finished product is lowered as described earlier. However, this method is accompanied by the drawback such as the inferior flowability, the inferior laser processing, the higher material costs. Thus, this means is not necessarily regarded as effective.
Here, therefore, the description will be made of a method for forming a ceiling plate by use of the resin whose linear expansion coefficient is smaller such as LCP.
The LCP is a resin that provides a good molding flowability even as its pure material grade, while it has a smaller linear expansion coefficient that matches that of metal.
On the other hand, polymer is not easily intermingled with this resin when it joins with the resin fused in the metallic mold. As a result, the weld strength is lower than the general polymer by a half or a quarter approximately. Also, this resin material has a drawback that its molding shrinkage coefficient or linear expansion coefficient is subjected to a greater anisotropy.
When the ceiling plate is molded with the LCP, it is important to pay careful attention to the gate positions to control the weld forming positions so that the mechanical performance and product capability are not spoiled due to the weld positions. Also, in some cases, it may be necessary to modify the product shape in order to control the weld forming positions.
Also, if the gate position control, the product shape modification, or some other control are not effective enough in dealing with the welds, there is a need for pushing out the welds from the finished product by devising the metallic mold in order to shift resin to a specific location compulsorily or to control orientation of resin or to operate the weld forming portions.
As specific examples, a resin pool may be installed on the outer side of the finished product but in the vicinity of the weld forming portions so that the structure is arranged to enable the mold dowel to advance to or retract from this resin pool. In other words, the mold dowel which has advanced into the resin pool is retracted from the resin pool at given timing during the filling of the fused resin. Thus, resin on the weld portion and the circumference thereof is allowed to flow in this resin pool for disposing thereof. In this respect, the mold dowel that advances to and retracts from the resin pool is controlled to shift by the driving means which is individually arranged. Also, the resin in the resin pool for its disposition is cut off together with the gate portion at the time of mold removal or after the removal.
In this way, the weld lines are partly removed from the finished product, hence making it possible to suppress the reduction of the mechanical strength of the finished product.
Also, as described above, the method for controlling the movement of the mold dowel by arranging the resin pool in the metallic mold is an effective means not only for the weld molding control, but for the resin anisotropy control and the resin orientation control as well. Then, this method is applicable to enhancing the forming precision, and also, to controlling the linear expansion coefficient, and the like.
Along with the provision of the higher resolution required for the liquid jet recording apparatus from now on as described above, the kind of the resin material that can be used suitably for the ceiling plate thereof is considerably limited. Also, even with the material that can be applied to the ceiling plate suitably, it becomes more difficult to control the molding thereof, and to improve the forming precision further still. Also, the structure of the metallic mold should become more complicated in order to control the resin orientation and perform the weld control as well. The molding apparatus should be specially arranged for the purpose, which requires more investment in facilities. There is also a problem that the higher molding techniques should obviously be required.
The present invention is designed with a view to making the overall improvement of the formability of the ceiling plate, including the structure of the ceiling plate, the forming precision and the dimensional stability thereof in order to attain the higher resolution technologies and techniques required for the liquid jet recording apparatus to be put on the market from now on. Then, it is an object of the invention to minimize the warping of the lower face of the liquid flow path walls, and at the same time, to overcome the weak points in the performance of the conventional ceiling plate, such as the thermal expansion and robustness, and some other related problems.
Now, with a view to solving the problems discussed above, the liquid jet recording head of the present invention is structured as given below.
The liquid jet recording head comprises a substrate member provided with discharge energy generating elements for generating ink discharge energy corresponding to a plurality of ink flow paths; a plurality of grooves corresponding to the plurality of ink flow paths; an orifice plate provided with ink discharge ports for discharging ink each communicated with each one end of the grooves; an ink liquid chamber communicated with each of the grooves at the other end thereof for supplying ink to each of the grooves; and an ink supply port for supplying ink to the ink liquid chamber. Then, a ceiling plate member, which is formed integrally with the grooves, the orifice plate, the ink liquid chamber, and the ink supply port, and the substrate member are bonded to form a plurality of ink discharge paths. For this ink jet recording head, the ceiling plate member is structured with a first substrate comprising the grooves and the orifice plate, and a second substrate comprising the ink liquid chamber and the ink supply port, and then, the first substrate and the second substrate are bonded by means of the bicolor molding to be integrally molded.
Also, the liquid jet recording head comprises a substrate member provided with discharge energy generating elements for generating ink discharge energy corresponding to a plurality of ink flow paths; a plurality of grooves corresponding to the plurality of ink flow paths; an orifice plate provided with ink discharge ports for discharging ink each communicated with each one end of the grooves; an ink liquid chamber communicated with each of the grooves at the other end thereof for supplying ink to each of the grooves; and an ink supply port for supplying ink to the ink liquid chamber. Then, a ceiling plate member, which is formed integrally with the grooves, the orifice plate, the ink liquid chamber, and the ink supply port, and the substrate member are bonded to form a plurality of ink discharge paths. For this ink jet recording head, the ceiling plate member is structured with an ink contact unit substrate provided with portions to be in contact with ink, and a non-ink contact unit substrate provided with portions not to be in contact with ink, and then, the ink contact unit substrate and the nonink contact unit substrate are integrally molded by means of the polychromatic molding.
Also, the liquid jet recording head comprises a substrate member provided with discharge energy generating elements for generating ink discharge energy corresponding to a plurality of ink flow paths; a plurality of grooves corresponding to the plurality of ink flow paths; an orifice plate provided with ink discharge ports for discharging ink each communicated with each one end of the grooves; an ink liquid chamber communicated with each of the grooves at the other end thereof for supplying ink to each of the grooves; and an ink supply port for supplying ink to the ink liquid chamber. Then, a ceiling plate member, which is formed integrally with the grooves, the orifice plate, the ink liquid chamber, and the ink supply port, and the substrate member are bonded to form a plurality of ink discharge paths. For this liquid jet recording head, the ceiling plate member comprises a first substrate provided with the grooves, the orifice plate, and a part of the outer wall of the ink liquid chamber to be generating elements for generating ink discharge energy corresponding to a plurality of ink flow paths; a plurality of grooves corresponding to the plurality of ink flow paths; an orifice plate provided with ink discharge ports for discharging ink each communicated with each one end of the grooves; an ink liquid chamber communicated with each of the grooves at the other end thereof for supplying ink to each of the grooves; and an ink supply port for supplying ink to the ink liquid chamber. Then, a ceiling plate member, which is formed integrally with the grooves, the orifice plate, the ink liquid chamber, and the ink supply port, and the substrate member are bonded to form a plurality of ink discharge paths. For this liquid jet recording head, the ink liquid chamber is separated into plural divisions by the separation walls integrally formed with the ceiling plate member, and the ceiling plate member comprises a first substrate provided with the grooves, the orifice plate, a part of the outer wall of the ink liquid chamber to be in close contact with the substrate member, and a part of the separation walls to be in close contact with the substrate member, and a second substrate provided with the portion of the ink liquid chamber with the exception of the first substrate, the separation walls with the exception of the first substrate, and the ink supply port, and then, the first substrate and the second substrate are bonded by means of the bicolor molding to be integrally molded.
Also, the liquid jet recording head comprises a substrate member provided with discharge energy generating elements for generating ink discharge energy corresponding to a plurality of ink flow paths; a plurality of grooves corresponding to the plurality of ink flow paths; an orifice plate provided with ink discharge ports for discharging ink each communicated with each one end of the grooves; an ink liquid chamber communicated with each of the grooves at the other end thereof for supplying ink to each of the grooves; and an ink supply port for supplying ink to the ink liquid chamber. Then, a ceiling plate member, which is formed integrally with the grooves, the orifice plate, the ink liquid chamber, and the ink supply port, and the substrate member are bonded to form a plurality of ink discharge paths. For this liquid jet recording head, the orifice plate is divided into the orifice plate lower part having the discharge ports, and the orifice plate upper part excluding the discharge port with above the discharge ports as the boundary, and the ceiling plate member comprises a first substrate provided with the grooves and the orifice plate lower part, and a second substrate provided with. the orifice plate upper part, the ink liquid chamber, and the ink supply port, and then, the first substrate and, the second substrate are integrally molded by means of the bicolor molding.
Also, the liquid jet recording head comprises a substrate member provided with discharge energy generating elements for generating ink discharge energy corresponding to a plurality of ink flow paths; a plurality of grooves corresponding to the plurality of ink flow paths; an orifice plate provided with ink discharge ports for discharging ink each communicated with each one end of the grooves; an ink liquid chamber communicated with each of the grooves at the other end thereof for supplying ink to each of the grooves; and an ink supply port for supplying ink to the ink liquid chamber. Then, a ceiling plate member, which is formed integrally with the grooves, the orifice plate, the ink liquid chamber, and the ink supply port, and the substrate member are bonded to form a plurality of ink discharge paths. For this liquid jet recording head, the orifice plate is divided into the orifice plate lower part having the discharge ports, and the orifice plate upper part excluding the discharge port with above the discharge ports as the boundary, and the ceiling plate member comprises a first substrate provided with the grooves and the orifice plate lower part, and a part of the portion of the outer wall of the ink liquid chamber to be in close contact with the substrate member, and a second substrate provided with the orifice plate upper part, the ink liquid chamber with the exception of the first substrate, and the ink supply port, and then, the first substrate and the second substrate are bonded means of the bicolor molding to be integrally molded.
Also, the liquid jet recording head comprises a substrate member provided with discharge energy generating elements for generating ink discharge energy corresponding to a plurality of ink flow paths; a plurality of grooves corresponding to the plurality of, ink flow paths; an orifice plate provided with ink discharge ports for discharging ink each communicated with each one end of the grooves; an ink liquid chamber communicated with each of the grooves at the other end thereof for supplying ink to each of the grooves; and an ink supply port for supplying ink to the ink liquid chamber. Then, a ceiling plate member, which is formed integrally with the grooves, the orifice plate, the ink liquid chamber, and the ink supply port, and the substrate member are bonded to form a plurality of ink discharge paths. For this liquid jet recording head, the ink liquid chamber is separated into plural divisions by the separation walls integrally molded with the ceiling plate member, and the orifice plate is divided into the orifice plate lower part having the discharge ports, and the orifice plate upper part excluding the discharge port with above the discharge ports as the boundary, and the ceiling plate member comprises a first substrate provided with the grooves and the orifice plate lower part, and a part of the portion of the outer wall of the ink liquid chamber to be in close contact with the substrate member, and the separation walls with the exception of the first substrate, and a second substrate provided with the orifice plate upper part, the ink liquid chamber with the exception of the first substrate, the separation walls with the exception of the first substrate, and then, the ink supply port, and the first substrate and the second substrate are bonded by means of the bicolor molding to be integrally molded.
Also, the liquid jet recording head comprises a substrate member provided with discharge energy generating elements for generating ink discharge energy corresponding to a plurality of ink flow paths; a plurality of grooves corresponding to the plurality of ink flow paths; an orifice plate provided with ink discharge ports for discharging ink each communicated with each one end of the grooves; an ink liquid chamber communicated with each of the grooves at the other end thereof for supplying ink to each of the grooves; and an ink supply port for supplying ink to the ink liquid chamber. Then, a ceiling plate member, which is formed integrally with the grooves, the orifice plate, the ink liquid chamber, and the ink supply port, and the substrate member are bonded to form a plurality of ink discharge paths. For this liquid jet recording head, the orifice plate is divided into the orifice plate lower part having the discharge ports, and the orifice plate upper part excluding the discharge port with above the discharge ports as the boundary, and the ceiling plate member comprises an ink contact unit substrate provided with the portions to be in contact with ink, and a non-ink contact unit substrate provided with the portions not to be in contact with ink, and then, the ink contact unit substrate and the non-ink contact unit substrate are bonded by means of the polychromic molding to be integrally molded.
Also, the liquid jet recording head comprises a substrate member provided with discharge energy generating elements for generating ink discharge energy corresponding to a plurality of ink flow paths; a plurality of grooves corresponding to the plurality of ink flow paths; an orifice plate provided with ink discharge ports for discharging ink each communicated with each one end of the grooves; an ink liquid chamber communicated with each of the grooves at the other end thereof for supplying ink to each of the grooves; and an ink supply port for supplying ink to the ink liquid chamber. Then, a ceiling plate member, which is formed integrally with the grooves, the orifice plate, the ink liquid chamber, and the ink supply port, and the substrate member are bonded to form a plurality of ink discharge paths. For this liquid jet recording head, the surface of the orifice plate is formed in the uniform plane or the uniform curve, and the ceiling plate is structured with a first substrate comprising the orifice plate including at least the circumferential portion of the discharge ports, and the grooves, and a second substrate comprising the portions with the exception of the portions becoming the first substrate, and then, the first substrate and the second substrate are bonded by means of the bicolor molding to be integrally molded.
In accordance with the present invention, the complicatedly configured ceiling plate member is divisionally molded, and integrally molded by means of the polychromic molding. Particularly, the thinner thickness portion of the orifice plate and the minute portion of the ink flow path walls are separated to be in a simple configuration. Therefore, it becomes possible to mold these portions in good precision. In other words, the portions that require high molding precision are simply configured, and then, the portions thus simplified in its configuration, and the other portions are integrally molded by means of the polychromic molding. The ceiling plate member thus completed becomes a highly precise finished product. Also, with the polychromic molding combined with various resins, fillers, metallic alloys, and the like, it becomes possible to mold a highly functional ceiling plate member in high precision, which has never been implement by means of the monochromatic molding.
The orifice plate and the ink flow path walls of the ceiling plate member, which are most important portions, require the high precise transfer, the smaller warping, the laser processibility, the durability of metallic mold, and the like for the molded surface thereof. Also, for the performance aspect, the high robustness, the lower linear expansion coefficient are required, among some others. If the ceiling plate member is molded with resin that contains fillers or the like, it becomes difficult to satisfy the condition of the molded surface, although the aforesaid aspect of the performance can be satisfied. As a result, the material that contains fillers cannot be used in accordance with the conventional art.
Therefore, if the ceiling plate member is divided into a first substrate formed with the orifice plate and the ink flow path walls, and a second substrate formed with all the other portions, and then, integrally molded by means of the bicolor molding, the condition of the molded surface can be satisfied for the first substrate even by molding it with the conventional material. Here, meanwhile, the second substrate should be molded with the material that improves the performance aspect of the ceiling plate member.
Also, with the first substrate having a simple configuration having a uniform thickness, the transferability, the molding precision, and the surface precision of the ink flow path wall lower face are enhanced. Then, when these substrates are bonded by means of the polychromic molding, it becomes possible to implement the enhancement of the performance aspects of the completed ceiling plate member, such as the elastic modulus, the linear expansion coefficient, which have been the drawback of the conventional art without sacrificing the requirement of the molded surface.
Now, in order to effectively improve the performance of the first substrate (the orifice plate and the ink flow path walls) by the application of the property of the material used for the second substrate, it become important to configure both the first and second substrates and arrange the configuration of the bonded portion accordingly. In other words, among some others, the second substrate should embrace the circumference of the ink flow path portion; the first substrate should be molded as thin as possible; and the voluminal ratio of the second substrate should be larger than the first substrate. In this manner, the structural aspect should be developed, and then, if the second substrate is molded with the molding material that can implement the improvement of the performance of the first substrate, it becomes possible to complement the weakness of the first substrate.
It has been difficult to mold the ceiling plate member that can satisfy both functions of the molded surface and performance required for the orifice plate and ink flow path walls of the ceiling plate member by means of the monochromatic molding. However, with the complex molding of the ceiling plate member, such as the polychromatic molding using plural materials, it becomes possible to satisfy both functions, which are incompatible to each other, that is, the aspects of the molded surface and the performance thereof.
Therefore, for the first substrate, pure resin having a good flowability and transferability is used to mold it in high precision. For the second substrate, the resin (or metallic alloy) filled with fillers is used, and if both of them are integrally molded by means of the bicolor molding. Then, it is made possible to complete the multiply functional ceiling plate member which has never been obtainable conventionally.
In this respect, since the first substrate is simply configured and molded with the material having a good flowability, the molding precision is enhanced. Meanwhile, although the configuration is complicated, the second substrate is molded with the material that contains fillers to make it possible to implement the precise molding, because the molding shrinkage, anisotropy, and other molding condition are improved. As a result, the integrally molded product by means of the polychromic molding becomes a ceiling plate member having high precision, high robustness, resistance to the thermal expansion, and the performance aspect thereof is enhanced significantly.
Also, since the first substrate is molded individually and separated from the ink liquid chamber and ink supply port, which cause the creation of welds, it becomes possible to prevent the gas generated from resin and the air in the metal mold from being stagnated in the interior of the metal mold, hence degrading the transferability of the molded product. As a result, it is possible to deal sufficiently with molding the ceiling plate provided with highly densified nozzles for use of the higher resolution liquid jet recording head which should be made available from now on. On the other hand, the welds may be created for the second substrate, but having no minute portions, the molding precision is not required for it as in the case of the first substrate. With the selection of material having high elastic modulus, and lower linear expansion coefficient for the second substrate, it is attempted to improve the performance of the ceiling plate as a whole.
Also, when the resin that contains fillers or the like is used for the second substrate, the first and second substrates can be bonded firmly by means of the bicolor molding if the base resin of the second substrate is the same as the pure material used for the first substrate. Then, the second substrate can implement the first substrate structurally with respect to the thermal expansion, the elastic modulus, and some other aspects of its performance. In this way, the weakness of the first substrate is improved effectively.
Also, on the bonded interface between the first and second substrates, the irregular lines are arranged in the form of ribs, bellows, bosses, seats, rectangles, or the like to make the bonding area greater and bonding stronger between them.
Also, with the irregular lines arranged on the bonded surface between the first and second substrates, while the second substrate is bonded with resin having a smaller linear expansion coefficient, it becomes possible to suppress the voluminal changes of the first substrate even when the ceiling plate member is placed under the environment having great temperature changes, because the second substrate can block it structurally with the irregular lines arranged on the boundary surface between them.
Furthermore, if the irregular lines should be formed to be undercut in the releasing direction of the first substrate and the second substrate, both of them are molded integrally even if both of them are molded with different materials or the bonding strength is smaller between them. As a result, the second substrate can implement the weakness of the first substrate.
Also, if the arrangement of the irregular lines are made in the same direction as the arrangement direction of the ink flow path walls, it becomes possible to suppress the deviation of the relative positions of the discharge heaters and the ink flow paths up to the ink discharge ports.
Also, if the ceiling plate member is divided into the ink contact unit substrate that is in contact with ink and the non-ink contact unit substrate that is not in contact with ink, and then, if it is molded by the polychromic molding, there is no need for the non-ink contact unit substrate to be provided with the ink resistive performance. As a result, it becomes possible to select various molding materials, and fillers, and to mold this substrate by use of an inexpensive base resin, a highly precise base resin, or the base resin which has an excellent mechanical strength with various fillers being contained in any one of them.
Also, if the ceiling plate is structured integrally by means of the three color molding with the ink discharge substrate formed by the orifice plate and ink flow path walls; the ink supply unit substrate formed by the inner wall of the ink liquid chamber, and the inner wall of the ink supply port; the outer circumferential portion substrate formed by the circumferential portions of the ceiling plate, each of the substrates can be molded with the optimal material, such as the material preferably suitable for the, precise molding of the ink supply unit substrate, the material which has a good resistance to ink for the ink supply unit substrate, and an inexpensive material for the outer circumferential portion substrate, respectively.
Also, if the structure is arranged so that the surface layer of the orifice plate is separated from the orifice plate main body, and that the orifice plate surface layer is molded with the material having a good water repellency. Then, this water-repellent surface layer is bonded with the ceiling plate member by means of the bicolor molding or polychromic molding to be integrally molded. In this manner, the water repellency treatment given to the orifice plate surface layer in the secondary process in the conventional art is now executed at the time of the bicolor or polychromic molding to simplify the manufacturing process of the ceiling plate member.
Also, when the polychromic molding is executed, the core portion of the metallic mold is processed to be the same configuration for the two locations in the case of the bicolor molding in general, for example. On the other hand, the two locations of the cavity portion of the metallic mold is given the processing that matches the molding configuration on the primary side and also, the one that matches the molding configuration on the secondary side, respectively. Now, if the groove (nozzle) portion should be transferred to the core side, two sets of the expensive mold dowels are needed for use of the groove transfer to increase the manufacturing costs of the metallic mold. Therefore, with the arrangement of the metallic mold structure so that the groove portion is transferred for molding on the cavity side, the manufacturing costs of the metallic mold for use of the bicolor molding become inexpensive. In this respect, the same statement is applicable to the polychromic molding where the third or more material injections are performed.
Also, the groove portion is molded on the primary side, the groove portion, which has been released once from the cavity on the primary side, this portion is in the released state (in the state where it is not in contact with the metallic mold) in the interior of the cavity on the secondary side, hence being easily influenced at the time of resin molding on the secondary side. In other words, since the resin on the secondary side is filled, while flowing on the boundary surface corresponding to the upper face of the groove portion, the thermal stress, the inertial force on the resin on the secondary side, the shearing force from the resin on the secondary side, and the like are caused to act to make the molding precision of the groove portion inferior. In order to avoid the groove, portion from being affected by the following continuous resin injection, the injection molding is arranged to be performed on the secondary side. Then, it becomes possible to secure the stabilized molding precision. Also, naturally, it is advisable to mold this portion lastly when the polychromic molding is performed.
Also, since the ink liquid chamber lower face portion and the groove portion are molded integrally, it is possible to form the step between the ink liquid chamber lower face and the ink flow path wall lower face in good precision even if the ceiling plate member is molded by means of the polychromic molding. In other words, the dowel portions that transfer the ink liquid chamber lower face and the ink flow path lower face are arranged in one and the same metal mold. As a result, it becomes easier to secure the step precision between them even at the time of manufacturing the metallic mold.
Further, for the ink jet recording head capable of discharging many kinds of ink with a plurality of ink liquid chambers, the separation wall lower part portion in the ink liquid chamber and the ink liquid chamber outer wall lower part portion are structured integrally with the groove portion. Then, it also becomes possible to mold the steps between the separation wall lower face, the ink liquid chamber lower face, and ink flow path wall lower face in good precision.
Therefore, the configuration of the substrate having the portions that require high precision is made as simple as possible, and such simply configured part and the other part are integrated by means of the polychromic molding. Then, the completed ceiling plate member is the product molded in high precision. Also, with the polychromic molding combined with various resins, ceramics, metals, fillers, and the like, it becomes possible to mold the multiply functional ceiling plate member in high precision that has never been implemented by means of the monochromatic molding.
For the ceiling plate member, the orifice plate and the ink flow path walls are most important portions, and the following aspects are important as to the molded surface. In other words, for the orifice plate, it is required to provide the highly precise flatness and the dimensional stability so as to form the discharge ports for which the desired shape and the desired length are secured. For the ink flow path walls, it is required to provide the highly precise transfer with the smallest possible warping in order to supply ink assuredly and execute the stabilized ink discharges. Also, if the discharge ports and ink flow path walls are formed by means of laser processing, the laser processibility of the molding resin is extremely important.
On the other hand, the higher robustness and lower linear expansion coefficient are required for the aspect of the performance. In order to satisfy such aspect of the performance, it is necessary to improve the ceiling plate molding material. Here, the compound resin that contains fillers is effective. However, if molding is executed with material that contains fillers, the condition of the molding surface described above is affected by the presence of fillers, although the performance is satisfied. As a result, it has been impossible to use the material which is filled with fillers up to now.
Therefore, if the ceiling plate member is structured to be divided into the first substrate provided with the orifice plate lower part including the discharge ports and the ink flow path walls, and the second substrate provided with the orifice plate upper part, the ink liquid chamber, and the ink supply port, and then, integrally by means of the bicolor molding, the first substrate is molded with the conventional material, hence satisfying the condition of the molded surface of the orifice plate (discharge ports) and the ink flow path wall portion. On the other hand, the second substrate is molded with the material prepared for the purpose of improving the performance of the ceiling plate member. Then, both of them is integrated by means of the bicolor molding to provide a higher performance for the ceiling plate member, which has never been implemented conventionally.
The portion whose thickness is extremely small, such as the orifice plate, has a large resistance to the resin flow, and if the thinner thickness portion of the kind is extended over the wide range, it becomes extremely difficult to fill resin. For that matter, the viscosity of resin should be lower, and the flowability thereof should be higher. As a result, the selection range becomes narrower for the resin to be used. On the other hand, it becomes severer to control the temperature of metallic mold, the resin temperature, the injection pressure, injection speed, and to adjust the metallic mold, among some other molding conditions required.
Now, therefore, the orifice plate is divided into the upper part and the lower part, and then, the molding is performed separately in two processing steps, such as the orifice plate lower part is molded at the time of the first substrate molding, and the orifice plate upper part is molded at the time of the second substrate molding. In this manner, the area of thinner thickness portion becomes smaller per molding process. Then, as compared with the case where the entire body of the orifice plate is molded at a time, the formability is enhanced significantly, and the molding precision is further enhanced as well.
Particularly, for the first substrate having the minute ink flow path walls and the thinner orifice plate, the orifice plate is divided, and then, when the upper part of the orifice plate is removed, the area of the thinner thickness portion is made smaller. Thus, the difficulty with which the first substrate should be molded is reduced significantly.
Also, if the structure is arranged so that the ceiling plate member is divided into the first substrate provided with the orifice plate lower part including the discharge ports, ink flow path walls, and a part of the ink liquid chamber outer wall portion which is in contact with the substrate member (heater board), and the second substrate provided with the orifice plate upper part, the ink liquid chamber portion excluding the first substrate, and the ink supply port, and that these substrates are integrated by means of the bicolor molding, the lower face portion of the ink liquid chamber outer wall, and the groove portion are molded in one and the same process. Therefore, the step between the ink liquid chamber lower face and the ink flow path wall lower face is molded in good precision even if the ceiling plate member is molded by means of the polychromic molding. In other words, the dowel portions, which transfer the ink liquid chamber lower face and the ink flow path wall lower face, are arranged in one and the same metallic mold to make it easier to secured step precision between them when the metallic mold is manufactured.
Furthermore, for the liquid jet recording head capable of discharging many kinds of ink with the arrangement of plural ink liquid chambers, the separation wall lower face of the ink liquid chamber, the lower face portion of the ink liquid chamber outer walls, and the groove portion are molded in one and the same process. Therefore, the step between the separation wall lower face, the ink liquid chamber lower face, and ink flow path wall lower face is also molded in good precision.
In this respect, the second substrate is complicatedly configured, but it is molded with the material that contains fillers or the like. As a result, the mold shrinkage, anisotropy, and some other molding condition are improved to make it possible to perform the highly precise molding. Therefore, the finished product having the second substrate and the first substrate integrated by means of the polychromic molding becomes the ceiling plate member provided with high precision, high robustness, resistance to thermal expansion, which has never been implemented conventionally, and its performance is enhanced significantly.
Also, the surface of the orifice plate is in the uniform plane or in the uniform curve. As a result, unlike the case where the step is formed on the surface of the orifice plate, it becomes possible to wipe off (carry out wiping) the remaining ink on the orifice plate reliably. Thus, the size of the capping member can be made smaller. Also, the blade can slidably move on the surface of the orifice plate to make it possible to enhance the durability of the blade accordingly. As a result, the blade can be produced with an inexpensive material. Furthermore, there is no step on the surface of the orifice plate completely or the step, if any, is extremely small. The resultant distance from the discharge ports to a recording medium becomes smaller to make it possible to enhance the impact accuracy of ink to be discharged from the discharge ports.
Particularly, the orifice plate is divided into the upper and lower parts, and the first substrate is arranged to contain the minute liquid flow path walls, and the lower part of the thinner orifice plate. In this manner, the area of the thinner thickness portions becomes smaller to facilitate the molding of the first substrate. Also, with the simple configuration having the uniform thickness, it becomes possible for the first substrate to enhance the transferability, the molding precision, and the surface precision of the liquid flow path wall lower face, among some others. Then, the first and second substrates are bonded by means of polychromic bonding, hence attempting the improvement of the elastic modulus, the linear expansion coefficient, and some other aspects of the performance of the completed ceiling plate.
Now, if the second substrate is molded with the material that contains fillers, the texture of the fillers is orientated in the arrangement direction of the groove line, provided that the gate is arranged to allow the molding material to flow to the vicinity above the groove line of the first substrate. The robustness, the thermal expansion ratio, and other properties, which are provided for the molding material, are made available to the maximum in the arrangement direction of the groove line.
Also, for the first substrate, the area where the molding material should be filled becomes narrower than the case where the entire body of the ceiling plate member is molded at a time, and at the same time, the distance from the gate portion to the liquid flow path walls is shortened, hence allowing the molding material to arrive at the liquid flow path wall portion without any excessive detoured passages. As a result, it becomes possible to fill the molding material into the metallic mold quickly and effectively at the time of the injection process. Then, during the dwelling process, the pressure thus swelled acts upon in all the directions in the metallic mold to make it possible to significantly enhance the transferability of the liquid flow path walls which present the minute portions. As a result, an easier implementation is possible from now on for the transfer of the liquid flow path wall portions than the conventional art even if the discharge ports are arranged in density higher still.
Also, the gate is positioned at the end face of the orifice plate for the first substrate to enable the molding material injected from the gate to advance straightly up to the discharge port circumferential portion. Therefore, the pressure loss of the molding material is made extremely smaller to facilitate filling the molding material in the metallic mold when the first substrate is molded. In this manner, the stepped portions are removed from the surface of the orifice plate to make the entire body of the orifice plate thinner, hence implementing the transfer of the thinner thickness portion of the orifice plate and minute portions of the liquid flow path walls.
Further, the second substrate is molded with the material enforced with fillers or the like, and at the same time, a part of the orifice plate is molded by the second substrate. Then, it becomes possible to make the strength of the orifice plate greater.
As described above, The configuration of the first substrate is simplified to make it possible to arrange the gates efficiently. Therefore, the higher filling and the highly precise molding are possible when the first substrate is molded. Furthermore, there is no need for the provision of any steps for the orifice plate, hence facilitating the cleaning operation and the capping, among some others. On the other hand, if the second substrate is molded with the material filled with fillers or the like (resin, metal, ceramics, or the like), it becomes possible to obtain a higher robustness, a lower thermal expansion coefficient, a higher molding precision, and the like. In other words, with the first and second substrates integrated by means of the bicolor molding, it becomes possible to complete the multiply functional ceiling plate member in high precision, which has never been obtainable conventionally.